P=spm_select(Inf,'nifti');
N=nifti(P);
vol = zeros(numel(N),1);
for i=1:numel(N)
    dat = N(i).dat(:,:,:);
    dat = dat(isfinite(dat));
    s = sum(dat(:));
    vv = abs(det(N(i).mat(1:3,1:3)))/(100^3);
    vol(i) = s*vv;
end

